JP2013216549A - Manufacturing apparatus of silicon carbide single crystal and manufacturing method of silicon carbide single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing apparatus of a silicon carbide single crystal and a manufacturing method of a silicon carbide single crystal that can efficiently sublimate a raw material and can manufacture a high-quality silicon carbide single crystal.SOLUTION: A manufacturing apparatus 1 of a silicon carbide single crystal includes: a crucible 50 including a crucible body 30 that has an opening and in which a raw material 20 of a silicon carbide single crystal is arranged, and a cover 40 that plugs the opening of the crucible body 30; and a heating coil 80 that is located in an outside of a side part 30b of the crucible body 30 and performs induction heating of the crucible 50, and includes a bottom side heating coil 90 that is located in an outside of a bottom part 30a of the crucible body 30 opposing to the opening and performs induction heating of the crucible 50.

Description

  The present invention relates to a silicon carbide single crystal manufacturing apparatus and a silicon carbide single crystal manufacturing method using a sublimation recrystallization method.

  Conventionally, as a method for producing a silicon carbide single crystal, a method of sublimating a raw material of a silicon carbide single crystal and recrystallizing the sublimated raw material is widely known (see, for example, Patent Document 1).

  Specifically, the raw material is disposed on the bottom side of the crucible. A seed crystal is disposed on the lid side of the crucible. A heating coil is arranged outside the side of the crucible. By passing a high-frequency current through the heating coil, the heating coil induction-heats the crucible. Thereby, the temperature inside a crucible rises and a raw material sublimes. The sublimated raw material is recrystallized on the seed crystal, and a silicon carbide single crystal grows. Thus, the silicon carbide single crystal was manufactured.

JP 2001-26495 A

  One method for producing a high-quality silicon carbide single crystal is a method of growing a silicon carbide single crystal while slowing the growth rate of the silicon carbide single crystal. By reducing the growth rate, the stress generated in the growing silicon carbide single crystal is reduced. As a result, defects are less likely to occur in the silicon carbide single crystal, and a high-quality silicon carbide single crystal can be manufactured.

  In order to slow the growth rate, the temperature on the bottom side of the crucible and the temperature on the lid side of the crucible are brought close to each other to reduce the temperature gradient inside the crucible. Thereby, the temperature difference between the growth surface of the silicon carbide single crystal and the raw material becomes small, and the growth rate becomes slow.

  However, since the temperature at which the silicon carbide single crystal grows has an upper limit, when the temperature difference is reduced, the raw material is difficult to sublime. As a result, the raw material remained without sublimation, a sufficiently large silicon carbide single crystal could not be produced, and the raw material could not be sublimated efficiently.

  Further, as the raw material is sublimated, the raw material is carbonized to produce carbide powder. In some cases, the carbide powder soared and carbon as the carbide powder was taken into the single crystal. As a result, a high quality silicon carbide single crystal may not be manufactured.

  Therefore, the present invention has been made in view of such a situation, and a silicon carbide single crystal manufacturing apparatus and a silicon carbide single crystal that can efficiently sublimate a raw material and can manufacture a high-quality silicon carbide single crystal. It aims to provide a method.

  In order to solve the above-described problems, the present invention has the following features. A feature of the present invention is that a crucible body having an opening and having a silicon carbide single crystal material disposed thereon, a crucible having a lid for closing the opening of the crucible body, and a side portion of the crucible body An apparatus for producing a silicon carbide single crystal, which is located outside and has a heating coil for induction heating the crucible, is located outside the bottom of the crucible body facing the opening, and induction heats the crucible The gist is to have a bottom side heating coil.

  According to the characteristic of this invention, it has the bottom part side heating coil which is located in the outer side of the bottom part of a crucible main body, and induction-heats a crucible. Since the bottom side heating coil is located outside the bottom of the crucible body, it heats the bottom of the crucible body. Thereby, the heating temperature of a raw material rises as it goes to the bottom part of a crucible. Therefore, even if the temperature gradient inside the crucible is reduced, the temperature of the surface of the raw material facing the seed crystal can be increased as the raw material sublimates. For this reason, it can sublime without leaving a raw material, and a raw material can be sublimated efficiently.

  Since the raw material is heated as it approaches the bottom of the crucible body, the raw material is sublimated and carbonized sequentially from the raw material located on the bottom side. Accordingly, since the raw material carbide powder is located on the bottom side, the carbide powder hardly rises. As a result, a high quality silicon carbide single crystal can be manufactured.

  The bottom side heating coil may be spiral.

  Another feature of the present invention is that a crucible body having an opening and having a silicon carbide single crystal material disposed thereon, a crucible provided with a lid for closing the opening of the crucible body, and the crucible body A heating coil for inductively heating the crucible, located outside the bottom of the crucible body facing the opening, and having a bottom side heating coil for inductively heating the crucible. A silicon carbide single crystal manufacturing method for manufacturing a silicon carbide single crystal using an apparatus for manufacturing a silicon carbide single crystal, comprising the steps of placing the raw material in the crucible and heating the raw material, In the step of heating the raw material, the gist is to heat the crucible by the heating coil and the bottom side heating coil.

  In the step of heating the raw material, the current flowing through the bottom side heating coil may be changed relative to the current flowing through the heating coil.

  According to the present invention, the raw material can be sublimated efficiently, and a high-quality silicon carbide single crystal can be produced.

FIG. 1 is a schematic cross-sectional view of a silicon carbide single crystal manufacturing apparatus 1 according to this embodiment. FIG. 2 is a plan view of the bottom side heating coil 90 viewed from the direction A of FIG. FIG. 3 is a flowchart for illustrating the method for manufacturing the silicon carbide single crystal according to the present embodiment. FIG. 4 is an explanatory diagram for illustrating the Z-axis direction of the silicon carbide single crystal manufacturing apparatus 1 according to the present embodiment. FIG. 5 is a graph for explaining the temperature distribution inside the crucible 50 according to the present embodiment. FIG. 6 is a graph for explaining a temperature distribution inside a conventional crucible. FIG. 7 is a plan view of the bottom side heating coil 90 according to another embodiment. FIG. 8 is a plan view of the bottom side heating coil 90 according to another embodiment.

  An example of a silicon carbide single crystal manufacturing apparatus and a silicon carbide single crystal manufacturing method according to the present invention will be described with reference to the drawings. Specifically, (1) a schematic configuration of the silicon carbide single crystal manufacturing apparatus 1, (2) a method for manufacturing a silicon carbide single crystal, (3) operational effects, and (4) other embodiments will be described.

  In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. It should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones. Accordingly, specific dimensions and the like should be determined in consideration of the following description. It goes without saying that the drawings include parts having different dimensional relationships and ratios.

(1) Schematic configuration of silicon carbide single crystal manufacturing apparatus 1 A schematic configuration of the silicon carbide single crystal manufacturing apparatus 1 according to the present embodiment will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view of a silicon carbide single crystal manufacturing apparatus 1 according to this embodiment. FIG. 2 is a plan view of the bottom side heating coil 90 viewed from the direction A in FIG.

  As shown in FIG. 1, a silicon carbide single crystal manufacturing apparatus 1 (hereinafter, abbreviated as apparatus 1 as appropriate) includes a crucible 50 having a crucible body 30 and a lid 40, a quartz tube 70, a heating coil 80, and interference prevention. The coil 85, the bottom side heating coil 90, the heat insulating material 150, and the guide member 200 are included. Note that the z direction is a direction parallel to the central axis passing through the center of the crucible body 30 and the center of the lid body 40, and the direction orthogonal to the z direction is the x direction.

  The crucible 50 includes a crucible body 30 and a lid body 40. The crucible body 30 has an opening. The crucible body 30 is a cylindrical container. The crucible body 30 has a bottom portion 30a and side portions 30b. The bottom portion 30 a constitutes the bottom surface 33 of the crucible body 30. The bottom 30a faces the opening. The side portion 30 b constitutes the side surface 35 of the crucible body 30. One end portion of the side portion 30b forms an opening, and the other end portion of the side portion 30b is in contact with the bottom portion 30a.

  In the crucible body 30, a raw material 20 (also referred to as a sublimation raw material) of silicon carbide single crystal (hereinafter, abbreviated as single crystal as appropriate) is disposed. Specifically, the raw material 20 is disposed on the bottom surface 33 of the crucible body 30 from the opening of the crucible body 30.

  The lid 40 closes the opening of the crucible body 30. The lid 40 has a convex portion. The opening of the crucible body 30 is closed by fitting the convex portion into the opening. In this embodiment, the convex part of the cover body 40 and the crucible main body 30 are formed with threads that mesh with each other. The lid body 40 has a surface 41 facing the bottom surface 33 side of the crucible body 30. A pedestal 45 is formed on the surface 41. A seed crystal is disposed on the pedestal 45. Therefore, in the z direction, the seed crystal 100 is disposed at one end of the crucible 50 (that is, the lid 40), and the other end of the crucible 50 opposite to the one end of the crucible 50 (that is, the crucible body 30). The raw material 20 is arranged at the bottom 30a). For this reason, the seed crystal 100 and the raw material 20 are opposed. The crucible 50 is disposed inside the quartz tube 70. Specifically, the crucible 50 is disposed at the bottom of the quartz tube 70.

  The heating coil 80 is provided on the outer periphery of the quartz tube 70. That is, the heating coil 80 is located outside the side portion 30 b of the crucible body 30. The heating coil 80 includes a heating coil 80a and a heating coil 80b. The heating coil 80 a is located on the bottom surface 33 side of the crucible body 30. The heating coil 80b is located on the lid 40 side. By passing a high-frequency current through the heating coil 80, the heating coil 80 induction-heats the crucible 50. Thereby, the temperature inside the crucible 50 rises and the raw material 20 sublimates. The temperature on the lid 40 side is preferably lower than the temperature on the bottom surface 33 side of the crucible body 30 so that the raw material 20 is easily recrystallized. The crucible 50 is covered with a heat insulating material 150.

  As shown in FIG. 1, the bottom side heating coil 90 is located outside the bottom 30 a of the crucible body 30. In the present embodiment, the bottom side heating coil 90 is located outside the bottom of the quartz tube 70.

  As shown in FIG. 2, in the present embodiment, the bottom side heating coil 90 has a spiral shape. Accordingly, the bottom side heating coil 90 extends in a curved shape that moves away from the center as it turns. The bottom side heating coil 90 is arranged so that the bottom side heating coil 90 can be seen in a spiral shape when viewed from the z direction. When the width of the bottom side heating coil 90 is constant in the orthogonal direction orthogonal to the direction in which the bottom side heating coil 90 extends, the interval between the bottom side heating coils 90 in the orthogonal direction is constant. Accordingly, the bottom heating coil 90 is an Archimedean spiral.

  Both ends of the bottom side heating coil 90 are connected to electrodes. Similarly to the heating coil 80, the bottom side heating coil 90 causes the crucible 50 to be inductively heated by passing a high-frequency current through the bottom side heating coil 90. Since the bottom part side heating coil 90 is located outside the bottom part 30a of the crucible body 30, the bottom part 30a of the crucible body 30 is mainly heated.

  In this embodiment, the bottom side heating coil 90 overlaps with the crucible 50 as viewed from the z direction. The bottom side heating coil 90 is smaller than the bottom 30 a of the crucible body 30. Accordingly, the bottom side heating coil 90 is positioned inside the outer edge of the bottom 30a when viewed from the z direction.

  The guide member 200 regulates the growth range of the single crystal. Further, the guide member 200 guides the sublimated raw material to the seed crystal 100. In the present embodiment, the guide member 200 has a cylindrical truncated cone shape with both ends opened.

(2) Manufacturing method of silicon carbide single crystal The manufacturing method of the silicon carbide single crystal which concerns on this embodiment is demonstrated, referring FIGS. 1-3. FIG. 3 is a flowchart for illustrating the method for manufacturing the silicon carbide single crystal according to the present embodiment.

  As FIG. 3 shows, the manufacturing method of the silicon carbide single crystal which concerns on this embodiment is provided with arrangement | positioning process S1 and heating process S2. In the method for manufacturing a silicon carbide single crystal according to the present embodiment, the silicon carbide single crystal is manufactured using the apparatus 1 described above.

(2.1) Arrangement process S1
The placement step S1 is a step of placing the silicon carbide single crystal raw material 20 in the crucible 50. Further, in the arranging step S1 according to the present embodiment, the seed crystal 100 made of silicon carbide is arranged in the crucible 50.

  The seed crystal 100 is placed on the lid 40 of the crucible 50. Specifically, the seed crystal 100 is fixed to the pedestal 45 using an adhesive. The raw material 20 is disposed in the crucible body 30. Specifically, the raw material 20 is disposed from the opening of the crucible body 30 to the bottom surface 33 of the crucible body 30. Thereby, seed crystal 100 is arranged on one side of crucible 50, and raw material 20 is arranged on the other side of crucible 50.

  A seed crystal 100 is prepared from silicon carbide. Specifically, a silicon carbide single crystal processed into a flat plate shape is prepared. The seed crystal 100 may include a protective layer that suppresses sublimation of silicon carbide from the back surface.

  The silicon carbide contained in the raw material 20 may be prepared by any manufacturing method. For example, silicon carbide manufactured by a chemical vapor deposition method (CVD method) may be used, or a silicon carbide precursor is generated from a silicon-containing raw material and a carbon-containing raw material, and the generated silicon carbide precursor is fired. Silicon carbide obtained by doing so may be used. It is preferable to use a material with few impurities as the raw material 20.

(2.2) Heating step S2
The heating step S2 is a step of heating the raw material 20.

  The crucible 50 is heated by the heating coil 80 and the bottom side heating coil 90. Specifically, current is passed through the heating coil 80 and the bottom side heating coil 90 to heat the crucible 50. The heated crucible body 30 heats the raw material 20. Generally, the heating temperature is 2000 ° C to 2500 ° C. The heating coil 80 a and the heating coil 80 b are adjusted so that the temperature on the lid body 40 side is slightly lower than the temperature on the bottom side of the crucible body 30. If the sublimation temperature of the raw material 20 is exceeded, the raw material 20 will sublime.

  The bottom 30a is heated by the bottom side heating coil 90. Therefore, the raw material 20 is heated as it approaches the bottom 30a.

  It is preferable to change the current flowing through the bottom side heating coil 90 relative to the current flowing through the heating coil 80. For example, by adjusting the current flowing through the bottom side heating coil 90, the current flowing through the bottom side heating coil 90 can be changed relative to the current flowing through the heating coil 80. Thereby, the temperature distribution inside the crucible 50 (that is, inside the raw material 20) can be changed to a desired state.

  The sublimated raw material 20 is recrystallized on the seed crystal 100. Thereby, the silicon carbide single crystal starts to grow. The silicon carbide single crystal is grown until a silicon carbide single crystal of a desired size is obtained.

  The growth rate of the silicon carbide single crystal is preferably 0.1 mm / h or less, and the stress generated in the growing silicon carbide single crystal is preferably 10 MPa or less. Under such conditions, since the grown silicon carbide single crystal is less likely to have defects, a high-quality silicon carbide single crystal can be produced.

(3) Operational Effect As shown in FIG. 4, in the central axis passing through the bottom 30 a of the crucible 50 and the lid 40, the direction from the bottom 30 a toward the lid 40 is the Z axis. The temperature on the Z axis is defined as T (Z). On the Z axis, the position of the bottom surface 33 is Z = 0, the position of the surface 20a of the raw material 20 facing the seed crystal 100 is Z = Zsur, and the position of the surface of the seed crystal 100 facing the raw material 20 is Z = Zseed. And

  In order to continuously maintain the crystal growth, the temperature gradient from the bottom of the sublimation raw material (Z = 0 in FIGS. 4 and 5) through the sublimation raw material surface (Zsur) to the seed crystal surface (Zseed). As shown in FIG. That is, if the bottom of the sublimation raw material is Z = 0 and the Z axis is taken as shown in FIG. 3 and the temperature at an arbitrary Z is expressed as T (Z), the condition for continuously maintaining crystal growth is: The following expression (1) is satisfied.

dT (Z) / dZ <0 (where 0 <Z <Zseed) (1)
By satisfying this condition, since the raw material is always supplied from the bottom side of the sublimation raw material to the surface of the sublimation raw material, crystal growth can be continued continuously. If the temperature distribution has a maximum point as shown in FIG. 6, the sublimation raw material filled on the seed crystal 100 side from the maximum point (Zmax) is diffused and transported to the seed crystal 100 side to form a crystal. Contribute to growth. On the other hand, the sublimation raw material filled on the bottom 30a side from the maximum point is diffused and transported on the bottom 30a side and recrystallized on the bottom side. For this reason, the raw material is not supplied to the surface of the sublimation raw material (that is, Zsur). For this reason, crystal growth cannot be continued continuously.

  The silicon carbide single crystal manufacturing apparatus 1 according to this embodiment includes a bottom side heating coil 90 that heats the crucible 50 and is located outside the bottom 30 a of the crucible body 30. Since the bottom side heating coil 90 heats the bottom 30a, the raw material 20 is heated as it approaches the bottom 30a. For this reason, as shown in FIG. 5, the temperature distribution of the crucible 50 satisfies the above formula (1). That is, in order to slow down the growth rate of the single crystal, even if the temperature on the bottom 30a side and the temperature on the lid 40 side are close, the temperature of the surface 20a of the raw material 20 is lower than the temperature of the growth surface of the single crystal. Never become. Therefore, the above formula (1) can always be satisfied, and the raw material 20 can be sublimated efficiently. As a result, a sufficiently high-quality silicon carbide single crystal can be manufactured.

  The raw material for the silicon carbide single crystal is silicon carbide (SiC). SiC is decomposed by heating into SiC2, Si2C, and Si2 that are gas components and C (carbon) that is a powder of a raw material carbide. Therefore, carbide powder is generated as the raw material is sublimated. The carbide powder accumulates at the bottom of the crucible body 30 where the raw material has been disposed, as the raw material is sublimated.

  In the conventional silicon carbide single crystal manufacturing apparatus, the crucible is heated from the outside of the side portion of the crucible. For this reason, the raw material arrange | positioned at the side part side of the crucible tends to sublimate, and the raw material was carbonized in an order from the raw material located in the outer peripheral side of a raw material. The carbide powder located on the seed crystal side is likely to rise with the sublimation of the raw material. As the soared carbide powder adheres to the growing single crystal, the carbide powder (that is, carbon) is taken into the produced single crystal. As a result, a single crystal with reduced quality was obtained.

  In the silicon carbide single crystal manufacturing apparatus 1 according to the present embodiment, the raw material 20 is heated as it approaches the bottom portion 30a, so that the raw material is sublimated and carbonized sequentially from the raw material 20 located on the bottom portion 30a side. Accordingly, since the raw material carbide powder is located on the bottom 30a side, the carbide powder hardly rises up. As a result, a high quality silicon carbide single crystal can be manufactured.

  Moreover, since the silicon carbide single crystal manufacturing apparatus 1 according to the present embodiment has the spiral bottom heating coil 90, the bottom 30a of the crucible body 30 can be easily induction-heated uniformly. For this reason, a raw material can be sublimated efficiently and a high quality silicon carbide single crystal can be manufactured.

  Further, it is preferable to change the current flowing through the bottom side heating coil 90 relative to the current flowing through the heating coil 80. As the crystal growth proceeds, the amount of the raw material 20 changes, so that the temperature distribution inside the raw material 20 changes. By changing the current flowing through the bottom side heating coil 90 relative to the current flowing through the heating coil 80, the temperature distribution inside the crucible 50 (ie, inside the raw material 20) can be changed to a desired state. it can. As a result, a high-quality silicon carbide single crystal can be manufactured.

  It is desirable to adjust the current flowing through the bottom side heating coil 90 so that the temperature of the surface 20a of the raw material 20 is constant and the temperature distribution inside the raw material 20 is the same temperature distribution from the start of crystal growth.

(4) Other Embodiments Although the contents of the present invention have been disclosed through the embodiments of the present invention, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. The present invention includes various embodiments not described herein. Accordingly, the present invention includes various embodiments not described herein.

  Specifically, in the above-described embodiment, the bottom side heating coil 90 has a spiral shape, but is not limited thereto. For example, as shown in FIG. 7, a single-turn coil may be used.

  Moreover, although the bottom part side heating coil 90 was the spiral shape comprised by the curvilinear member so that it might approach a center as it turned, it is not restricted to this. For example, as shown in FIG. 8, the bottom side heating coil 90 may have a spiral shape constituted by a plurality of linear members so as to approach the center while bending at a right angle.

  As described above, the present invention includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

  DESCRIPTION OF SYMBOLS 1 ... Silicon carbide single crystal manufacturing apparatus, 20 ... Raw material, 20a ... (Raw material) surface, 30 ... Crucible body, 30a ... Bottom part, 30b ... Side part, 33 ... Bottom face, 35 ... Side face, 40 ... Cover body, 41 ... Surface 45, pedestal, 50 crucible, 70 quartz tube, 80, 80a, 80b heating coil, 85 interference prevention coil, 90 bottom heating coil, 100 seed crystal, 150 thermal insulation, 200 guide Element

Claims (4)

A crucible having an opening and a crucible body on which a raw material of the silicon carbide single crystal is disposed; and a lid for closing the opening of the crucible body;
A silicon carbide single crystal manufacturing apparatus having a heating coil for induction heating of the crucible, located outside a side portion of the crucible body,
An apparatus for producing a silicon carbide single crystal, comprising a bottom side heating coil that is positioned outside the bottom of the crucible main body facing the opening and induction-heats the crucible.   The silicon carbide single crystal manufacturing apparatus according to claim 1, wherein the bottom side heating coil is a spiral heating coil. A crucible having an opening and a crucible body on which a raw material of the silicon carbide single crystal is disposed; and a lid for closing the opening of the crucible body;
A heating coil for inductively heating the crucible, located outside the side of the crucible body,
A silicon carbide single crystal that produces a silicon carbide single crystal using a silicon carbide single crystal production apparatus that is located outside the bottom of the crucible body facing the opening and has a bottom side heating coil for induction heating the crucible A manufacturing method of
Placing the raw material in the crucible, and heating the raw material,
A method for producing a silicon carbide single crystal, wherein in the step of heating the raw material, the crucible is heated by the heating coil and the bottom side heating coil.   The method for producing a silicon carbide single crystal according to claim 3, wherein in the step of heating the raw material, a current flowing through the bottom portion side heating coil is changed relative to a current flowing through the heating coil.

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